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Etchants containing filterable surfactant

a technology of surfactant and etching rate, which is applied in the direction of basic electric elements, electrical equipment, chemistry apparatus and processes, etc., can solve the problems of physical wetting by etchant solution on a substrate becoming more difficult, and achieve the effects of excellent surface active properties, superior wetting, and desirable etching ra

Inactive Publication Date: 2006-09-26
KMG ELECTRONICS CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

"The present invention provides improved silicon dioxide etching solutions with desirable etching rates and superior wetting compared to prior art etching solutions. The etchants of the invention retain excellent surface active properties after filtration. The etching solution of the invention after a filtration through medium of the order of 0.1 micron yields a product in which the etchant retains an effective level of surfactant, is essentially free of metal ions, has a superior rate of etching at etching temperatures used for prior art solutions, provides better wetting characteristics for improved etch uniformity, and does not leave residues or adversely affect photoresist adhesion. The addition of a novel multi-component surfactant to aqueous etching solutions meets the criteria described in this patent. The improved etchants of the invention are obtained by adding a small amount of the tri-component surface active agent to solutions of concentrations between about 0.1% and 99% by weight of the compounds described herein."

Problems solved by technology

As integrated circuit component dimensions become smaller, physical wetting by etchant solutions on a substrate becomes more difficult.

Method used

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  • Etchants containing filterable surfactant
  • Etchants containing filterable surfactant
  • Etchants containing filterable surfactant

Examples

Experimental program
Comparison scheme
Effect test

preparatory example

[0051]An aqueous solution of 10% of surfactant in 50% 2-propanol (by weight)[0052]i.e., refer to the reaction above of perfluorooctanoic acid and cycloheptyl amine.[0053]Composition of 100 g of 10% surfactant include:[0054]5 g Acid (approx. 99% purity)[0055]5 g amine (approx. 99% purity)[0056]45 g 2-propanol (approx. 99% purity)[0057]45 g deionized H2O

[0058]Various runs were conducted to demonstrate that the surfactant(s) met the desired criteria. Generally the experimental runs were carried out in pilot scale (1 lb. to 100 lbs. batches).

General Run

[0059]A preliminary testing was conducted prior to filtration to evaluate whether individual components of the claimed surfactant(s), would work individually, need modification, or require combining to give a basic understanding which would lead to synthesis of the surfactant(s) of the invention. Potential surfactant candidates were prepared and evaluated in an aqueous mixture comprised of about 35% by weight of ammonium fluoride, NH4F, a...

example 1

[0061]80 lbs. of an aqueous mixture comprised of 40% by weight of ammonium fluoride and 0.5% by weight of hydrofluoric acid (defined as BOE 100-1) was mixed with 500-ppm of surfactant “H” (a selected member of the claimed surfactant group as listed in Table I), by weight of the mixed etchant, and filtered through two 0.2-micron polyethersulfone (PES) filters. The surfactant mixture was not aggressively agitated, but circulated through filters runs for three days with interval samplings of approximately every four hours. The mean results are given in Table II below:

[0062]

TABLE IIBeforeAfterMeet SuccessProperties / CriteriaFiltrationFiltrationCriteria (Yes / No)Surface Tension1838Encouraged(dynes / cm2)Particulates (cts / ml)≧1.0 micron >3,00010Yes≧0.5 micron>10,00033YesFoamingInsignificantInsignificantYes[0063]The surface tension was found to increase following filtration. Data indicates the surfactants were removed during filtration, and failed to meet one of the success criteria. Another e...

example 2

[0064]200 ppm of surfactant “H” (Table I) were added into an aqueous mixture comprising of about 35% by weight of ammonium fluoride and about 6.3% by weight of hydrofluoric acid (defined as BOE 7-1), and without agitation, the mixture was circulated through two −0.2 μm filters (PES and Teflon or otherwise known as polytetrefluoroethylene or PTFE) and the results are given in Table III below:

[0065]

TABLE IIIBeforeAfterMeet SuccessProperties / CriteriaFiltrationFiltrationCriteria (Yes / No)ST (dynes / cm2)2036EncouragedPC:≧1.0 μm—6Yes≧0.5 μm—82YesFoamInsignificantInsignificantYes

[0066]Results similar to those of Example 1 were seen, despite different blends, concentrations of ammonium fluoride and hydrofluoric acid and different sets of filters (1 PES+1 Teflon instead of 2 PES). At this point, it was unknown whether the surfactant(s) filtered out or was not fully solubilized within the etching solution. A mechanical rotating blade mixer was introduced into the small pilot scale reactor to en...

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Abstract

An improved etching and cleaning composition for semiconductor devices is provided in which the etch solution incorporates a novel surfactant comprising a combination of a linear perfluorocarboxylic acid, a cyclic amine and an aliphatic alcohol.

Description

[0001]This invention relates to improved buffered oxide etchant and metal etchant compositions containing soluble surfactant additives. These additives are capable of maintaining reduced surface tensions for increased wetting stability and are useful in integrated circuit manufacture. Specifically, this invention relates to the utilization, in the surfactant composition, of a three-component surfactant blend comprising a combination of a linear perfluorocarboxylic acid, a cyclic alkylamine and an aliphatic alcohol. The three-component surfactant system of the invention is incorporated and finds utility in a known variety of etchants including for example: ammonium fluoride-hydrofluoric acid (HF) blends; ammonium fluoride HF—phosphoric acid (PA) blends; PA—nitric acid—acetic acid blends; PA-nitric acid-acetic acid-fluoboric acid-HF blends; PA—nitric acid—sulfuric acid—HF blends; nitric acid—sulfuric acid—HF blends; nitric acid-HF-acetic acid and nitric acid-sulfuric acid blends. Each...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): C09K13/00
CPCC09K13/08
Inventor MORI, ERIKHONG, BRIANCRAIG, JAMES
Owner KMG ELECTRONICS CHEM
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